Wave soldering of surface-mounting electronic devices on printed circuit board

Abstract

A system includes a device of the surface-mounting type having an insulating package provided with a mounting surface and a contact pin exposed on the mounting surface. The device is attached to an insulating board including a gluing surface and an opposite surface. The process for manufacturing the system includes forming through holes a contact region on the gluing surface. The mounting surface is glued to the gluing surface with the contact pin aligned with the contact region. Wave soldering is performed to electrically join the device to the board by hitting the opposite surface with a wave of soldering paste to form, by capillary action with the soldering paste ascending in the through holes up to the overflow on the gluing surface, a conductive contact electrically connecting the contact pin of the electronic device through a solder connection to the contact region of the electronic board.

What is claimed is: 
     
       1. A method for manufacturing an electronic system including at least one electronic device of the surface-mounting type having an insulating package provided with a mounting surface and at least one contact pin exposed on the mounting surface, and an electronic board having an insulating substrate for supporting electronic devices, the insulating substrate comprising a gluing surface and an opposite surface to the gluing surface, the method comprising:
 forming a plurality of through holes in at least one contact region on the gluing surface of the electronic board, 
 gluing on the gluing surface of the electronic board at least one electronic device, 
 aligning the at least one contact pin with the at least one contact region, 
 placing an electronic assembly comprising the at least one electronic device glued on the electronic board in a bath of soldering paste, and 
 wave-soldering the glued at least one electronic device to the electronic board, 
 wherein wave-soldering comprises:
 hitting the surface of the electronic board opposite to the gluing surface with a wave of soldering paste and forming, by capillary ascending of soldering paste in the through holes until overflowing on the gluing surface, at least one conductive contact contacting the at least one contact pin of the electronic device by soldering the at least one contact pin to the electronic board. 
 
 
     
     
       2. The method according to  claim 1 , wherein wave-soldering further comprises forming the at least one conductive contact integral with a corresponding thermally conductive path, adapted to dissipate heat generated by the at least one electronic device in operation. 
     
     
       3. The method according to  claim 1 , wherein forming a plurality of through holes comprises forming through holes perpendicular with respect to the gluing surface of the electronic board. 
     
     
       4. The method according to  claim 1 , wherein forming a plurality of through holes comprises forming through holes tilted with respect to the gluing surface of the electronic board. 
     
     
       5. The method according to  claim 4 , wherein forming the through holes tilted with respect to the gluing surface of the electronic board comprises: tilting the through holes forming each one with a corresponding opening on the bottom surface closer to the point of origin of the wave of soldering paste than a corresponding opening on the gluing surface. 
     
     
       6. The method according to  claim 1 , wherein forming a plurality of through holes further comprises defining a diameter of the through holes according to a density of the soldering paste and a thickness of the insulating substrate. 
     
     
       7. The method according to  claim 1 , wherein forming a plurality of through holes further comprises excluding at least one portion of at least one contact region from the forming of the plurality of through holes. 
     
     
       8. The method according to  claim 7 , further comprising using an adhesive in the excluded portions to attach the gluing surface of the electronic board to the at least one electronic device. 
     
     
       9. The method according to  claim 1 , wherein forming a plurality of through holes further comprises forming the through holes at a mutual distance decreasing in a propagation direction of the wave of soldering paste. 
     
     
       10. The method according to  claim 1 , wherein forming a plurality of through holes further comprises forming the through holes with a varying diameter along an extension from an aperture on the bottom surface to a corresponding aperture on the gluing surface. 
     
     
       11. The method according to  claim 1 , wherein forming a plurality of through holes further comprises forming the through holes with a diameter varying in the propagation direction of the wave of soldering paste. 
     
     
       12. A method, comprising:
 forming a plurality of through holes in at least one electrical contact region of an electronic board, said plurality of through holes extending between a gluing surface and an opposite surface of the electronic board, 
 gluing at least one electronic device of the surface-mounting type to the gluing surface of the electronic board, said electronic device comprising having an insulating package provided with a mounting surface and at least one contact pin exposed on the mounting surface over the at least one contact region, 
 wave-soldering the glued at least one electronic device to the electronic board by hitting the opposite surface of the electronic board with a wave of soldering paste that flows, by capillary action, in a manner ascending via the through holes from the opposite surface to overflow on the gluing surface to make at least one conductive contact between the at least one contact pin of the electronic device and the at least one contact region of the electronic board. 
 
     
     
       13. The method of  claim 12 , wherein gluing comprises inserting an adhesive between the mounting surface of the insulating package and an attachment region on the gluing surface of the electronic board. 
     
     
       14. The method of  claim 13 , wherein gluing further comprises inserting an adhesive between the at least one contact pin exposed on the mounting surface of the insulating package and an additional attachment region provided on at least one electrical contact region of an electronic board which is devoid of said plurality of through holes. 
     
     
       15. The method of  claim 12 , wherein wave-soldering further comprises forming the at least one conductive contact integral with a corresponding thermally conductive path, adapted to dissipate heat generated by the at least one electronic device in operation. 
     
     
       16. The method of  claim 12 , wherein forming a plurality of through holes comprises forming through holes perpendicular with respect to the gluing surface of the electronic board. 
     
     
       17. The method of  claim 12 , wherein forming a plurality of through holes comprises forming through holes tilted with respect to the gluing surface of the electronic board. 
     
     
       18. The method of  claim 17 , wherein forming the through holes tilted with respect to the gluing surface of the electronic board comprises: tilting the through holes forming each one with a corresponding opening on the bottom surface closer to the point of origin of the wave of soldering paste than a corresponding opening on the gluing surface. 
     
     
       19. The method of  claim 12 , wherein forming a plurality of through holes further comprises defining a diameter of the through holes according to a density of the soldering paste and a thickness of the insulating substrate. 
     
     
       20. The method of  claim 12 , wherein forming a plurality of through holes further comprises forming the through holes at a mutual distance decreasing in a propagation direction of the wave of soldering paste. 
     
     
       21. The method of  claim 12 , wherein forming a plurality of through holes further comprises forming the through holes with a varying diameter along an extension from an aperture on the bottom surface to a corresponding aperture on the gluing surface. 
     
     
       22. The method according to  claim 12 , wherein forming a plurality of through holes further comprises forming the through holes with a diameter varying in the propagation direction of the wave of soldering paste.